1. Field
Aspects relate to an image forming apparatus, and more particularly, to a charging apparatus using a charging tube.
2. Description of the Related Art
An image forming apparatus such as a printer, a facsimile machine, a copier, and a multifunction peripheral forms a predetermined image on a printing medium using electrophotography. Such an image forming apparatus generally carries out a charging process, a laser scanning process, a developing process, a transferring process, and a fusing process, in order to form an image. In the charging process, a charging apparatus electrically charges a photoconductive medium with a predetermined electric potential. In the laser scanning process, a laser scanning apparatus scans the photoconductive medium, which has been charged with the predetermined electric potential, with light, such that an electrostatic latent image corresponding printing data is formed on the photoconductive medium. In the developing process, a developing apparatus supplies toner to the photoconductive medium on which the electrostatic latent image is formed, thereby developing a toner image. In the transferring process, a transferring apparatus transfers the toner image formed on the photoconductive medium to a printing medium. In the fusing process, a fusing apparatus fuses the toner image onto the printing medium, thereby forming a predetermined image on the printing medium. After that, the printing medium is discharged out of the image forming apparatus and the image forming operation is completed.
In general, the charging apparatus is divided into an apparatus using a non-contact charging method and an apparatus using a contact charging method. The non-contact charging apparatus uses a corona discharge in general. The charging apparatus using the corona discharge has the advantage of charging a photoconductive medium uniformly, but has the disadvantage of generating a discharge product such as ozone. Therefore, an extra apparatus for processing the discharge product such as ozone is required and thus a size of the image forming apparatus increases and a manufacturing cost also increases.
The contact charging apparatus uses a charging roller which is in contact with a photoconductive medium and charges the photoconductive medium using a discharge occurring in a small gap between the charging roller and the photoconductive medium. The charging apparatus using the charging roller does not generate a discharge product such as ozone because it does not use a corona discharge, and makes it possible to achieve compactness of an image forming apparatus and reduce a manufacturing cost. However, there is a noise problem because the charging roller operates in contact with the photoconductive medium. Also, some of the low molecules forming the charging roller migrate to the photoconductive medium and thus there is a problem that the photoconductive medium is contaminated.